System and Method for Sealing a Fuel Nozzle

ABSTRACT

A system including a multi-tube fuel nozzle, including a first plate having a first plurality of openings, a plurality of tubes extending through the first plurality of openings in the first plate, wherein each tube of the plurality of tubes includes an air inlet, a fuel inlet, and a fuel-air mixture outlet, and a resilient metallic seal disposed along the first plate about the plurality of tubes.

BACKGROUND

The subject matter disclosed herein relates to a gas turbine engine and,more specifically, to a fuel nozzle for a combustor of the gas turbineengine.

A gas turbine engine generally includes a turbine and a combustor with afuel nozzle. A mixture of fuel and air combusts within the combustor togenerate hot combustion gases, which drive rotation of turbine blades inthe turbine and, in turn, a shaft coupled to a load, e.g., an electricalgenerator. The fuel-air mixture (e.g., uniformity of fuel-air mixing inthe combustor) can significantly impact power output, efficiency, andexhaust emissions of the gas turbine engine. In addition, combustion ofthe fuel-air mixture in the combustor can cause combustion dynamics,vibration, and thermal gradients, which can impact the performance andlife of various combustor components, such as the fuel nozzle. Forexample, the fuel nozzle may be subjected to thermal growth due to itsclose proximity to the hot products of combustion. Thesecombustion-related effects can complicate the design of gas turbineengines, particularly the combustors and fuel nozzles.

BRIEF DESCRIPTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In one embodiment, a system including a multi-tube fuel nozzle,including a first plate having a first plurality of openings, aplurality of tubes extending through the first plurality of openings inthe first plate, wherein each tube of the plurality of tubes includes anair inlet, a fuel inlet, and a fuel-air mixture outlet, and a resilientmetallic seal disposed along the first plate about the plurality oftubes.

In another embodiment, a system including a multi-tube fuel nozzle,including a plurality of fuel-air mixing tubes, wherein each tube of theplurality of fuel-air mixing tubes includes an air inlet, a fuel inlet,and a fuel-air mixture outlet, and a resilient metallic seal disposedabout the plurality of tubes, wherein the resilient metallic sealincludes at least one axially adjustable turn.

In another embodiment, a method including sealing a multi-tube fuelnozzle to a surrounding structure via a resilient metallic seal, whereinthe multi-tube fuel nozzle includes a plurality of tubes each having anair inlet, a fuel inlet, and a fuel-air mixture outlet, and expanding orcontracting the resilient metallic seal, while sealing, in response tothermal expansion or thermal contraction of the plurality of tubes orthe surrounding structure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of a turbine system having a micro-mixersystem according to an embodiment;

FIG. 2 is a cross-sectional perspective side view of a combustor withthe micro mixer system of FIG. 1 according to an embodiment;

FIG. 3 is a side view of a micro-mixer system according to anembodiment;

FIG. 4 is an exploded cross-sectional perspective view of a micro-mixersystem according to an embodiment;

FIG. 5 is an exploded perspective view of a fuel nozzle housing andmulti-tube fuel nozzles according to an embodiment;

FIG. 6 is a front view of a fuel nozzle housing according to anembodiment;

FIG. 7 is a front view of a fuel nozzle housing according to anembodiment;

FIG. 8 is a front view of a fuel nozzle housing according to anembodiment;

FIG. 9 is a partial cross-sectional view of a micro-mixer systemaccording to an embodiment;

FIG. 10 is a sectional view of the micro-mixer system of FIG. 9 alongline 10-10, illustrating an embodiment of a resilient metallic seal;

FIG. 11 is a front end view of an embodiment of a resilient metallicseal having a sector shaped configuration suitable for the sector fuelnozzles of FIGS. 4 and 5;

FIG. 12 is a sectional view of the fuel nozzle of FIG. 9 along line10-10, illustrating an embodiment of a resilient metallic seal having asingle turn or bend;

FIG. 13 is a sectional view of the fuel nozzle of FIG. 9 along line10-10, illustrating an embodiment of a resilient metallic seal havingmultiple turns or bends;

FIG. 14 is a sectional view of the fuel nozzle of FIG. 9 along line10-10, illustrating an embodiment of a resilient metallic seal havingmultiple turns or bends defining a bellows;

FIG. 15 is an exploded perspective view of an aft plate assemblyaccording to an embodiment;

FIG. 16 is a sectional view of the micro mixer system in FIG. 9 alongline 16-16, according to an embodiment;

FIG. 17 is a sectional view of an aft plate accordingly to anembodiment;

FIG. 18 is a rear perspective view of an inlet flow conditioner of afuel nozzle according to an embodiment;

FIG. 19 is a front perspective view of an inlet flow conditioneraccording to an embodiment;

FIG. 20 is a partial cross-sectional view of an inlet flow conditioneraccording to an embodiment;

FIG. 21 is a partial cross-sectional view of an inlet flow conditioneraccording to an embodiment; and

FIG. 22 is a partial cross-sectional view of an inlet flow conditioneraccording to an embodiment.

DETAILED DESCRIPTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

Embodiments of the present disclosure provide a micro-mixer system thatincludes an inlet flow conditioner, an aft plate assembly, a multi-tubefuel nozzle (e.g., a cylindrical or sector shaped fuel nozzle), aresilient metallic seal (e.g., a metallic bellows), and a fuel nozzlehousing. In certain embodiments, the multi-tube fuel nozzle may include5 to 1000, 10 to 500, 20 to 250, or 30 to 100 mixing tubes, which aregenerally parallel with one another in one or more groups (e.g., 1, 2,3, 4, 5, 6, or more groups). Each mixing tube may be approximately 0.25to 5, 0.5, to 3, or 1 to 2 centimeters in diameter. The plurality ofmixing tubes of the multi-tube fuel nozzle enable small scale mixing(e.g., micro-mixing) of fuel and air, thereby helping to improve theuniformity of fuel-air mixing in the combustor.

The fuel nozzle housing supports the micro-mixer system by coupling tothe inlet flow conditioner and aft plate assembly; and by receiving themulti-tube fuel nozzles. When assembled, the inlet flow conditioner andaft plate assembly cover the multi-tube fuel nozzles by coupling toopposite ends of the fuel nozzle housing. In certain embodiments, thefuel nozzle housing may include a first ring structure (i.e., an innerring structure) and a second ring structure (i.e., an outer ringstructure) coupled together by struts. The fuel nozzle housing mayreceive the multi-tube fuel nozzles within the inner ring structure anddeliver fuel radially to the multi-tube fuel nozzles. Specifically, thefuel nozzle housing may be configured to deliver fuel in a generallyradial direction through the outer ring structure, the inner ringstructure, and through the struts that couple the inner ring structureto the outer ring structure. The radial delivery of fuel enables the gasturbine system to include a simple end plate at the end of the combustor(e.g., an end plate with minimal or no fuel delivering apertures). Theradial fuel delivery may also increase space usage by the fuel nozzleswithin the combustor (i.e., the tubes of the multi-tube fuel nozzles mayoccupy the space previously used for fuel delivery through the endplate).

The struts in the fuel nozzle housing may include fuel carrying strutsand/or non-fuel carrying struts. The fuel nozzle housing struts enableradial fuel delivery and may increase resistance to vibration (e.g.,resonant vibration of the micro-mixer system). For example, the strutsmay increase the stiffness of the fuel nozzle housing and/or change theresonant frequency of the micro-mixer system. In addition, the strutsmay be aerodynamically shaped (e.g., an airfoil shape) to reduce thewake of compressed air passing between the outer ring structure and theinner ring structure. A reduction in the wake may also reduce vibrationin the micro-mixer system caused by compressed airflow through thecombustor.

Finally, the fuel nozzle housing enables a modular micro-mixer system.For example, the fuel nozzle housing may include a plurality of radialapertures that enable components of the micro-mixer system to easilyattach and detach. Specifically, the apertures may receive pins or otherfasteners that couple the inlet flow conditioner and the aft plateassembly to the fuel nozzle housing. Simple attachment and detachment ofthe inlet flow conditioner and aft plate assembly enable easy access to,maintenance of, or replacement of multi-tube fuel nozzles, the inletflow conditioner, the aft plate assembly, and the resilient metallicseal.

In operation, the micro-mixer system mixes air and fuel in a multi-tubefuel nozzle to create a fuel-air mixture. The fuel air mixture combustsin the combustor to create combustion gases that drive a turbine. Themulti-tube fuel nozzle may include a first plate with a first group ofopenings, a second plate with a second group of openings, and multipletubes extending through the groups of openings in the first and secondplates. Each tube of the tubes may have an air inlet at a first axialend, a fuel inlet between first and second axial ends, and a fuel-airmixture outlet at the second axial end. In particular, as discussedbelow, each tube is configured to premix (e.g., mixing on a small scale,or micro-mixing) fuel and air within the respective tube, and thenoutput a fuel-air mixture for combustion in a combustor (e.g., a turbinecombustor of a gas turbine engine). The temperature of the air enteringthe multi-tube fuel nozzle may be somewhat elevated, e.g., approximately200 to 500 degrees Celsius due to the work performed on the air throughcompression, while the fuel entering the tubes may be significantlycooler, e.g., approximately 20 to 250 degrees Celsius. In addition, thetubes may be susceptible to heating by the hot combustion products dueto their proximity to the combustion reaction. Thus, during operation(e.g., combustion in a combustion chamber), various components of themulti-tube fuel nozzle, housing structure, combustor, fuel supplyconduits, mounts, etc., may undergo thermal expansion at differentrates, thereby causing the more rapidly expanding components to impartforces against more slowly expanding components. For example, themultiple tubes of the multi-tube fuel nozzle may undergo a greater rateof thermal expansion than the surrounding fuel housing structure,mounts, combustor, and/or other structures.

In order to mitigate the induced stresses caused by thermal expansionand/or contraction of the component materials, the micro-mixer systemmay include a resilient metallic seal (e.g., a metallic bellows). Forexample, the metallic bellows may have a wall (e.g., annular ornon-annular wall) disposed about a space containing the plate and tubeassembly, wherein the wall has one or more turns or bends (e.g., a wave,oscillating, or zigzagging pattern) that are able to resiliently foldand unfold to enable expansion and contraction of the wall of themetallic bellows. Thus, the resilient adjustability (e.g., folding andunfolding of the wall) enables the metallic bellows to accommodatethermal expansion and contraction between the plate, the tube assembly,and the surrounding components. Without the resilient metallic seal(e.g., metallic bellows), axial displacement may result in stresseswithin the multi-tube fuel nozzle components, fuel/air leakages, loss ofpressure within the combustor, or other negative effects. When placedbetween the first plate and the housing structure, the resilientmetallic seal (e.g., metallic bellows) may expand or contract in anaxial direction to lessen the effects of thermal expansion orcontraction of the tubes, while maintaining a continuous working sealbetween chambers within the fuel nozzle. Additionally, the use of theresilient metallic seal may result in a more modular design, and thus,ease of construction, simple assembly/disassembly procedures, costeffective equipment replacement, and less maintenance down-time.

The micro-mixer system may also include the aft plate assembly toprovide additional protection of the multi-tube fuel nozzles (i.e.,resist thermal stresses). Specifically, the aft plate assembly may blockdirect contact between the combustion reaction in the combustor and themulti-tube fuel nozzles, as well as form an air cooling chamber forconvectively cooling the multi-tube fuel nozzles. While the air coolingchamber convectively cools the multi-tube fuel nozzles, the aft plateassembly blocks direct contact between the combustion reaction and themulti-tube fuel nozzle. Specifically, the aft plate assembly includes anaft plate with apertures that enable the fuel air mixture to exit themulti-tube fuel nozzles, while simultaneously covering the multi-tubefuel nozzles to resist heat transfer from the combustion reaction. Insome embodiments, the aft plate may include a thermal barrier coating toincrease thermal resistance to the combustion reaction. In still otherembodiments, the aft plate may include effusion cooling apertures thatreceive airflow from the air cooling chamber. The effusion coolingapertures form a cooling film on the aft plate, which protects the aftplate and reduces heat transfer. In other embodiments, the aft plateassembly may include an impingement plate configured to impinge coolingairflow against the aft plate before the airflow exits effusion coolingapertures, thus increasing thermal protection of the aft plate andreducing heat transfer to the multi-tube fuel nozzles. In operation, theimpingement plate accelerates the cooling airflow as it flows throughimpingement holes. The impingement holes direct the cooling airflow intocontact with the aft plate, where the cooling airflow absorbs heatbefore passing through the aft plate (e.g., through effusion coolingapertures and/or space between the aft plate and the tubes of themulti-tube fuel nozzles).

Finally, the micro-mixer system may include the inlet flow conditioner.The inlet flow conditioner is configured to filter airflow entering themicro-mixer system and evenly distribute the airflow into each of thetubes of the multi-tube fuel nozzles. In order to filter the airflowinto the micro-mixer system, the inlet flow conditioner may includeapertures that are smaller than the apertures in the tubes of themulti-tube fuel nozzles. Accordingly, debris capable of entering thetubes of the multi-tube fuel nozzle may be blocked by the inlet flowconditioner. As mentioned above, the inlet flow conditioner may evenlydistribute airflow into each of the tubes of the multi-tube fuelnozzles. Specifically, the inlet flow conditioner may include radialapertures and turning guides that channel airflow to the outermost tubesof the multi-tube fuel nozzles. However, in other embodiments, the inletflow conditioner may include angled apertures, in combination with orwithout turning guides, in order to channel airflow into the outermosttubes of the multi-tube fuel nozzles. By evenly distributing the airflowto the tubes of the multi-tube fuel nozzles, the multi-tube fuel nozzlesmix and distribute the fuel-air mixture in a suitable ratio for optimalcombustion, emissions, fuel consumption, and power output. Specifically,the micro-mixer system may reduce levels of undesirable emissions (e.g.,NOx, CO, CO₂, etc.) from a gas turbine system.

FIG. 1 is a block diagram of a gas turbine system 10. As described indetail below, the disclosed turbine system 10 may employ one or moreradially supported fuel nozzles (e.g., multi-tube fuel nozzles). Theturbine system 10 may use liquid or gas fuel, such as natural gas and/ora hydrogen-rich synthetic gas, to drive the turbine system 10. Asdepicted, the combustor 12 intakes a fuel supply 14, mixes the fuel withair for distribution and combustion within the combustor 12.Specifically, the combustor 12 includes a micro-mixer system 16 thatradially supports and provides fuel to multi-tube fuel nozzles. Incertain embodiments, the micro-mixer system 16 includes multiple fuelnozzles arranged around a central fuel nozzle. The multi-tube fuelnozzles mix and distribute the fuel-air mixture in a suitable ratio foroptimal combustion, emissions, fuel consumption, and power output.Specifically, the micro-mixer system 16 reduces levels of undesirableemissions (e.g., NOx, CO, CO₂, etc.) from the turbine system 10.

During operation, the fuel-air mixture combusts in a chamber within thecombustor 12, thereby creating hot pressurized exhaust gases. Thecombustor 12 directs the exhaust gases through a turbine 18 toward anexhaust outlet 20. As the exhaust gases pass through the turbine 18, thegases force turbine blades to rotate a shaft 22 along an axis of theturbine system 10. As illustrated, the shaft 22 may be connected tovarious components of the turbine system 10, including a compressor 24.The compressor 24 also includes blades coupled to the shaft 22. As theshaft 22 rotates, the blades within the compressor 24 also rotate,thereby compressing air from an air intake 26 through the compressor 24and directing the air into the multi-tube fuel nozzles and/or combustor12. The shaft 22 may also be connected to a load 28, which may be avehicle or a stationary load, such as an electrical generator in a powerplant or a propeller on an aircraft, for example. The load 28 mayinclude any suitable device capable of being powered by the rotationaloutput of the turbine system 10.

FIG. 2 is a cross-sectional perspective side view of a combustor 12according to an embodiment. As shown in FIG. 2, an axial direction oraxis 40 extends lengthwise along a central axis 41 of the combustor 12,a radial direction or axis 42 extends toward or away from the centralaxis 41 (e.g., perpendicular to the axis 40), and a circumferentialdirection 44 extends around the axial axis 40 and the central axis 41.The combustor 12 includes a downstream end 46 and an upstream end orhead end 48. The downstream end 46 is located near the first stage ofthe turbine 18, whereas the upstream end 48 is opposite the downstreamend 46 and located farther away from the first stage of the turbine 18.The combustor 12 includes multiple casings and walls that enclose thecombustor 12 and contain the compressed air and fuel. Starting from theupstream end 48, the combustor 12 includes an end casing 52 coupled toan end plate 54. As illustrated, the end plate 54 maybe a simple endplate, which includes a single fuel nozzle aperture 58. However, in someembodiments, the end plate 58 will not include the fuel nozzle aperture58. The endplate 54 may couple to the end casing 52 in a variety of waysincluding fasteners or welding. Opposite the end plate 54, the endcasing 52 couples to the fuel nozzle housing 56. In order to couple tothe fuel nozzle housing 56, the end casing 52 includes a flange 60,which enables attachment of the end casing 52 to the fuel nozzle housing56. For example, the end casing 52 may couple to the fuel nozzle housing56 with fasteners (e.g., threaded fasteners such as bolts) that extendthrough multiple apertures in the flange 60 and the fuel nozzle housing56.

Continuing in direction 40, the combustor 12 includes an aft casing 62.The aft casing 62 includes a first flange 64 and a second flange 66. Thefirst flange 64 enables the aft casing 62 to couple to the fuel nozzlehousing 56. Specifically, the first flange 64 may include multipleapertures 68 that allow fasteners (e.g., threaded fasteners such asbolts) to couple the aft casing to the fuel nozzle housing 56. Oppositethe first flange 64, the aft casing attaches or contacts a flow sleeve70, which aids in cooling the components of the combustor 16. Continuinginward in the radial direction 42 is a combustion liner 72. It is thecombustion liner 72 that contains the combustion reaction. An emptyspace is disposed between the flow sleeve 70 and the combustion liner72, and may be referred to as an annulus 74. The liner 72 extendscircumferentially 44 around the axis 41 of the combustor 12, the annulus74 extends circumferentially 44 around the liner 72, and the flow sleeve72 extends circumferentially 44 around the annulus 74. The annulus 74directs airflow to the combustor upstream end 48. More specificallyduring operation, airflow 76 from the compressor 24 enters an air plenumthat surrounds the flow sleeve 70. The flow sleeve 70 includes radialinjection apertures 78 that enable the compressed airflow 76 to passthrough the flow sleeve 70 and into the annulus 74. After the air 76passes through the apertures 78, the annulus 74 channels the compressedair 76 towards the upstream end 48. In the upstream end 48, thecompressed air 76 may be turned or redirected toward one or more fuelnozzles 80. The fuel nozzles 80 are configured to partially premix airand fuel to create a fuel air mixture 82. The fuel nozzles 80 dischargethe fuel air mixture 82 into a combustion zone 84, where a combustionreaction takes place. The combustion reaction generates hot pressurizedcombustion products 86. These combustion products 86 then travel througha transition piece 88 to the turbine 18, thereby driving turbine bladesto generate torque.

As explained above, the combustor includes a micro-mixer system 16. Themicro-mixer system 16 includes the fuel nozzle housing 56, fuel nozzles80, an inlet flow conditioner 90, and an aft plate assembly 92. As willbe explained in more detail below, the micro-mixer system 16 functionsto protect multi-tube fuel nozzles 80 from debris and thermalgrowth/gradients; and provides each of the micro-mixer tubes of thenozzles 80 with proper ratios of airflow and fuel, which reducesundesirable emissions. The micro-mixer system 16 may include multiplefuel nozzles 80, which include multi-tube fuel nozzles and/or other fuelnozzles (e.g., swirl vane nozzles). In the illustrated embodiment, themicro-mixer system 16 includes multi-tube fuel nozzles 94, supported bythe fuel nozzle housing 56, and a center pilot fuel nozzle 96. The fuelnozzles 80 combine fuel and air to create a fuel air mixture forcombustion in the combustion zone 84. The pilot nozzle 96, like themulti-tube fuel nozzles 94, combines fuel and air to create a fuel airmixture for combustion. However, the pilot nozzle 96 may help to anchorthe combustion flame for the remaining fuel nozzles 94.

FIG. 3 is a side view of a micro-mixer system 16 according to anembodiment. As explained above, the micro-mixer system 16 includes afuel nozzle housing 56, an inlet flow conditioner 90, and an aft plateassembly 92. The fuel nozzle housing 56 radially supports the multi-tubefuel nozzles 80 (i.e., within the fuel nozzle housing 56) and provides aconnection point for the inlet flow conditioner 90 and the aft plateassembly 92. In addition, the fuel nozzle housing 56 enables radial fueldelivery (i.e., in radial direction 42) to the fuel nozzles 80. Theradial support and fuel delivery enables the combustor 12 to use asimple endplate 54 and increase the usable surface area for themulti-tube fuel nozzles 94.

The fuel nozzle housing 56 includes a first ring structure 120 (e.g., anouter wall) and a second ring structure or mounting structure 122 (e.g.,an outer flange). As explained above, the fuel nozzle housing 56 couplesto the end casing 52 and the aft casing 62. Specifically, second ringstructure 122 couples to the end casing 52 and the aft casing 62, thussecuring the micro-mixer system 16 within the combustor 12. The firstring structure 120 and the second ring structure 122 may be concentricwith one another and coupled together with multiple struts 124 (e.g.,radial support arms or airfoils). The struts 124 may be integral to thefuel nozzle housing 56. For example, the first ring structure 120, thesecond ring structure 122, and the struts 124 may be machined fromstock, cast, or grown using an additive process. In other embodiments,the first ring structure 120, the second ring structure 122, and thestruts 124 may be joined by welding, brazing, bolts, or other fasteners.As illustrated, the struts 124 may be aerodynamically shaped. Forexample, the struts 124 may have an airfoil shape or another type ofaerodynamic shape. The aerodynamic shape enables the struts 124 toreduce an airflow wake as airflow passes in-between the first ringstructure 120 and the second ring structure 122. A reduction in the wakereduces vibration and improves airflow into the inlet flow conditioner90. The struts 124 may also enable radial fuel delivery to the fuelnozzles 94. Specifically, the struts 124 may include an aperture influid communication with apertures in the second ring structure 122 andthe first ring structure 124. Accordingly, fuel is then able to flowfrom an external source 125, coupled to fuel flanges 126, through thefuel nozzle housing 56 and into the fuel nozzles 94 instead of throughan end plate 54. The fuel nozzle housing 56 may also include coolingapertures 128. The cooling apertures 128 enable cooling airflow to flowinto the fuel nozzle housing 56 (e.g., in radial direction 42) to coolthe multi-tube fuel nozzles 94 and the aft plate assembly 92, thusextending the operating life multi-tube fuel nozzles 94 and the aftplate assembly 92.

FIG. 4 is an exploded cross-sectional perspective view of a micro-mixersystem 16. As illustrated, the micro-mixer system 16 may be a modularsystem facilitating attachment and detachment of components.Specifically, the micro-mixer system 16 may removably attach and detachthe inlet flow conditioner 90 and the aft plate assembly 92 from thefuel nozzle housing 56. The ability to attach and detach the inlet flowconditioner 90 and the aft plate assembly 92 provides easy access to thefuel nozzles 94 for maintenance or replacement. Furthermore, increasedmodularity may result in a simpler assembly/disassembly procedures, timeefficient maintenance procedures, smaller replacement jobs, andincreased performance.

As illustrated, the inlet flow conditioner 90 extends circumferentially44 about axis 41 and may have a generally annular wall with an outerdiameter 150 that is smaller than an inner diameter 152 of the firstring structure 120. The difference in diameters enables the inlet flowconditioner 90 to slide axially 40 into the first ring structure 120.The inlet flow conditioner 90 is then able to attach or mount with afirst mount 153. The first mount 153 may include the first ringstructure 120, multiple fasteners 154, apertures 156 in the first ringstructure 120, and apertures 158 in the inlet flow conditioner 90. Thefasteners 154 couples the inlet flow conditioner 90 to the first ringstructure 120 through apertures 156 in the first ring structure 120 andthe corresponding apertures 158 in the inlet flow conditioner 90. Thefasteners 154 may be bolts, rivets, pins, or other removable fasteners.Alternatively, the inlet flow conditioner 90 may couple to the firstring structure 120 through brazing, welding, or even welding/brazing incombination with bolts or rivets. In still other embodiments, thediameter 150 of the inlet flow conditioner 90 may be greater than thediameter 152 of the first ring structure 120, enabling the inlet flowconditioner 90 to slide axially 40 over and couple to the exterior ofthe first ring structure 120.

The aft plate assembly 92 extends circumferentially 44 about axis 41 andmay have a generally annular wall that may couple to the fuel nozzlehousing 56. The aft plate assembly 92 may define an outer diameter 160that is smaller than the inner diameter 152 of the first ring structure120. The difference in diameters enables the aft plate assembly 92 toslide axially 40 into the first ring structure 120. The aft plateassembly 92 attaches or mounts to the fuel nozzle housing 56 with asecond mount 161. The second mount 161 may include the first ringstructure 120, multiple fasteners 162, apertures 164, and apertures 166in the aft plate assembly 92. The fasteners 162 couple the aft plateassembly 92 to the first ring structure 120 through apertures 164 in thefirst ring structure 120 and corresponding apertures 166 in the aftplate assembly 92. The fasteners 162 may be bolts, rivets, pins, orother removable fasteners. Alternatively, the aft plate assembly 92 maycouple to the first ring structure 120 through brazing, welding, orwelding/brazing the rivets or bolts in place. To control cooling airfrom passing between the aft plate assembly 92 and the first ringstructure 120, the micro-mixer system 16 may include a seal 168 (e.g., ahoop seal) between the aft plate assembly 92 and the first ringstructure 120. In still other embodiments, the outer diameter 160 of theaft plate assembly 92 may be greater than the diameter 152 of the firstring structure 120, enabling the aft plate assembly 92 to slide axially40 over and couple to the exterior of the first ring structure 120.

FIG. 5 is a perspective front end view of an embodiment of the fuelnozzle housing 56, illustrating fuel nozzles 94 (e.g., multi-tube fuelnozzles). Specifically, FIG. 5 illustrates fuel nozzles 94 in varyingstages of assembly in fuel nozzle receptacles 190 of the fuel nozzlehousing 56. For example, in the illustrated embodiment, one of the fuelnozzles 94 is fully installed in a fuel nozzle receptacle 190, while asecond fuel nozzle 94 is ready to be inserted into a neighboring fuelnozzle receptacle 190. The remaining fuel nozzle receptacle 190 is empty(i.e., without an installed third fuel nozzle 94) for purposes ofillustration. In the illustrated embodiment, each fuel nozzle receptacle190 has a truncated-pie shaped perimeter 188, which may be defined byopposite curved sides 189 and opposite converging sides 191.Furthermore, the illustrated fuel nozzle housing 56 has three equallysized fuel nozzle receptacles 190, each having the truncated-pie shapedperimeter 188. In other embodiments, the fuel nozzle housing 56 may have2, 3, 4, 5, 6, 7, 8, 9, 10, or more fuel nozzle receptacles 190 withtruncated-pie shaped perimeters 188. However, each fuel nozzlereceptacle 190 may resemble any shape, such as circles, rectangles,triangles, pie-shapes, or any other suitable geometry.

The illustrated fuel nozzles 94 have a truncated-pie shaped perimeter91, which may be defined by opposite curved sides 93 and oppositeconverging sides 95. The truncated-pie shaped perimeter 91 is contouredor shaped to fit into the truncated-pie shaped perimeter 188 of thereceptacle 190. The fuel nozzles 94 include multiple micro-mixer tubes192 (e.g., mixing tubes) arranged within plates 194, 196, and 198. Incertain embodiments, the multi-tube fuel nozzle 94 may include 5 to1000, 10 to 500, 20 to 250, or 30 to 100 tubes 192, which are generallyparallel with one another along the axis 41. Each tube 192 may beapproximately 0.25 to 5, 0.5, to 3, or 1 to 2 centimeters in diameter.The plates 194, 196, and 198 are axially offset from one another bydistances 200 and 202 to form chambers with fuel nozzle housing 56. Inthe present embodiment, there are three support plates, but in otherembodiments there may two or more support plates (e.g., 2, 3, 4, 5, 6,etc.). In this manner, the plates 194, 196, and 198 support, space, andarrange the micro-mixer tubes 192 in a designated pattern. In theillustrated embodiment, the tubes 192 are exposed along the sides 93 and95 of each fuel nozzle 94. In other words, each fuel nozzle 94 does notinclude its own dedicated housing, but rather the fuel nozzle housing 56serves as a common or shared housing for the plurality of fuel nozzles94. As a result, each fuel nozzle 94 may be described as a bundle oftubes 192, which can be axially 40 inserted and removed from arespective receptacle 190 in the housing 56.

FIG. 6 is a front view of the fuel nozzle housing 56 configured tosupport multiple fuel nozzles 80 (e.g., multi-tube fuel nozzles 94,central fuel nozzle 96, etc.) and provides a connection point for theinlet flow conditioner 90 and the aft plate assembly 92. As explainedabove, the fuel nozzle housing 56 includes the first ring structure 120and the second ring structure 122. In order to couple the fuel nozzlehousing 56 to the neighboring combustor casings, the second ringstructure 122 includes a plurality of apertures 220. The apertures 220may receive fasteners (e.g., threaded fasteners or bolts) that enablethe fuel nozzle housing 56 to couple to flanges on the combustor endcasing 52 and the combustor aft casing 62. The first ring structure 120and the second ring structure 122 may be concentric with one anotherabout the axis 41. As illustrated, the first ring structure 120 definesan outer diameter 222 smaller than the inner diameter 224 of the secondring structure 122. The difference in the diameters 226 forms airflowpassages 228 between the first ring structure 120 and the second ringstructure 122. The airflow passages 228 enable air to flow through thefuel nozzle housing 56 in an upstream direction toward the endplate 54.

The airflow passages 228 are separated by struts 124 that couple thefirst ring structure 120 to the second ring structure 122. In theillustrated embodiment, the fuel nozzle housing 56 may include two kindsof struts: (1) fuel carrying struts 230; and (2) struts 232 that do notcarry fuel. The struts 124 may also be integral to the fuel nozzlehousing 56 and configured to reduce resonant vibration in the fuelnozzle housing 56. For example, the struts 124 may be aerodynamicallyshaped to reduce the wake from the airflow through the airflow passages228. In addition, the struts 124 may provide the appropriate amount ofstiffness to tune out resonant frequency vibrations or change theresonance frequency of the fuel nozzle housing 56. For example, in thepresent embodiment the fuel nozzle housing 56 includes three fuel struts230 and three support struts or structural struts 232. In otherembodiments, the fuel nozzle housing 56 may include more fuel struts 230(e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more), or more support struts232 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more). In otherembodiments, some or all of the struts 124 may be larger and/or stifferto tune resonant vibration or provide additional support at specificlocations within the fuel nozzle housing 56.

As explained above, the fuel nozzle housing 56 enables radial fuel 42delivery to the fuel nozzles 80. The fuel nozzle housing 56 receivesfuel through fuel flanges 126 that couple to an exterior surface 234 ofthe second ring structure 122. As fuel passes through the fuel flange126 it enters an aperture 236 in the second ring structure 122. Afterpassing through the aperture 236, the fuel enters the fuel strut 230,which includes an aperture 238 leading to an aperture 240 in the firstring structure 120. As the fuel passes through the second ring structure120, the fuel enters the fuel nozzle receptacle 190 for use by the fuelnozzles 80. As explained above, the radial support and fuel deliverythrough the fuel nozzle housing 56 enables simplification of theendplate 54, and increases the usable surface area for the multi-tubefuel nozzles 94 (e.g., the number and/or size of the micro-mixer tubes192) within the first ring structure 120.

In the present embodiment, there are three fuel nozzle receptacles 190separated by radial divider walls or plates 242. However, there may beany number of fuel nozzle receptacles 190 (e.g., 1, 2, 3, 4, 5, 6, ormore). As illustrated, the non-fuel struts 232 align with the plates 242with the fuel struts 230 centrally positioned between the walls 242.However, in other embodiments, the fuel struts 230 and non-fuel struts232 may be positioned elsewhere. The radial divider walls or plates 242couple to the first ring structure 120 and to a third ring structure 244(e.g., a first inner wall). The third ring structure 244 may beconcentric with the first ring structure 120 and the second ringstructure 122; and defines a central receptacle 246. The centralreceptacle 246 may be configured to receive a central fuel nozzle orpilot nozzle 96 that may help to anchor the combustion reaction of thesurrounding multi-tube fuel nozzles 94. However, in other embodiments,the central receptacle 246 may be configured to receive a roundmulti-tube fuel nozzle. Moreover, other embodiments may have a larger,smaller or no central receptacle 246. In the illustrated embodiment, thefuel nozzle receptacles 190 have a truncated-pie shaped perimeter 188,and the central receptacle 246 is circular. However, the fuel nozzlereceptacles 190 and central receptacle 246 may resemble any shape, suchas, circles, rectangles, triangles, pie-shapes, or any other suitablegeometry. As explained above, the fuel nozzle housing 56 (i.e., thefirst ring structure 120, the third ring structure 244, and radialdivider wall 242) beneficially provides a housing for the multi-tubefuel nozzles 94. Accordingly, each fuel nozzle 80 does not require itsown independent housing, and thus can be replaced at a lower cost.

FIG. 7 is a front view of a fuel nozzle housing 56 according to anembodiment. As illustrated, the fuel nozzle housing 56 radially couplesto six fuel flanges 126. The fuel nozzle housing 56 receives fuel fromthe fuel flanges 126 and delivers the fuel radially 42 to the fuelnozzle receptacles 190, for use by the fuel nozzles 80. As explainedabove, the fuel passes through apertures in the second ring structure122, the fuel struts 230, and the first ring structure 120 beforeentering the fuel nozzle receptacles 190. In the illustrated embodiment,each fuel nozzle receptacle 190 is fed by two fuel flanges 126. The twofuel flanges 126 carry the fuel from the second ring structure 122 tothe first ring structure 120 through two corresponding fuel struts 230.In other embodiments, there may additional fuel flanges 126 for each ofthe fuel nozzle receptacles (e.g., 1, 2, 3, 4, 5, or more fuel flanges126) that deliver fuel through a corresponding number of fuel struts 230(e.g., 1, 2, 3, 4, 5, or more fuel struts 230).

As further illustrated in FIG. 7, the radial plates 242 may includeapertures 248 that enable fuel to flow from one fuel nozzle receptacle190 to a neighboring fuel nozzle receptacle 190. For example, theapertures 248 may be distributed throughout the plates 242 to helpdistribute the fuel more evenly among the tubes 192 of the fuel nozzles94. By further example, the number (e.g., 1 to 1000), size (e.g.,diameter), shape (e.g., circular, oval, triangular, square, hexagonal,etc.), axial 40 position, and radial 42 position of the apertures 248may be varied to control the distribution of fuel among the receptacles190, and thus among the multiple tubes 192 of the fuel nozzles 94. Insome embodiments, each of the plates 242 may include no apertures 248,more apertures 248 (e.g., 0, 1, 2, 3, 4, 5, 10, 15, 20, 25 or moreapertures 248), or differ in the number of apertures 248 between plates242. For example, one of the plates 242 may include two apertures 248,while the remaining plates have five and ten apertures 248 respectively.In an embodiment with apertures 248 in the plates 242, there may befewer fuel flanges 126 and fuel struts 230, because fuel may flow freelybetween the fuel nozzle receptacles 190. Accordingly, a single fuelflange 126 and fuel strut 230 may supply all the fuel to the fuel nozzlereceptacles 190. Furthermore, FIG. 7 illustrates that the third ringstructure 244 may include apertures 250. The apertures 250 permit fuelin the fuel nozzle receptacles 190 to enter the central receptacle 246.In the present embodiment, there are three apertures 250, however, indifferent embodiments there may be different numbers of apertures 250(e.g., 0, 1, 2, 3, 4, 5, 10, 15, or more apertures 250). In still otherembodiments, the third ring structure 244 may include apertures 250 thatcommunicate only with some of the fuel nozzle receptacles 190. Forexample, the third ring structure 244 may only include apertures 250between the central receptacle 246 and one of the fuel nozzlereceptacles 190.

FIG. 8 is a front view of a fuel nozzle housing 56 according to anembodiment. In the illustrated embodiment, the fuel nozzle housing 56includes three fuel nozzle receptacles 190. Each of these fuel nozzlereceptacles 190 occupies approximately 120 degrees of the area withinthe first ring structure 120. Indeed, FIG. 8 illustrates an embodimentwithout a central receptacle, which was shown in previous figures. WhileFIG. 8 illustrates only three fuel nozzle receptacles 190, otherembodiments may include different amounts of fuel nozzle receptacles 190(e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more fuel nozzle receptacles190) separated by plates 242. Furthermore, each of these fuel nozzlereceptacles 190 may occupy equal or different amounts of area within thefirst ring structure. For example, one fuel nozzle receptacle 190 mayoccupy 180 degrees of the first ring structure 120, while the remainingfuel nozzle receptacles 190 occupy a respective 90 degrees.

FIG. 9 is partial cross-sectional view of a micro-mixer system 16according to an embodiment. As explained above, micro-mixer system 16includes the fuel nozzle housing 56, fuel nozzles 80, the inlet flowconditioner 90, and the aft plate assembly 92. The fuel nozzle housing56 radially supports the micro-mixer system 16 by coupling between theend casing 52 and the aft casing 62, or more specifically, by couplingto the flange 60 of the end casing 52 and the first flange 64 of the aftcasing 62. With the fuel nozzle housing 56 coupled between the endcasing 52 and the aft casing 62, the fuel nozzle housing 56 is able toradially support and radially supply fuel to the fuel nozzles 80. Thefuel nozzles 80 may be multi-tube fuel nozzles 94 or multi-tube fuelnozzles 94 in combination with a pilot fuel nozzle 96. In theillustrated embodiment, the fuel nozzle housing 56 supports multi-tubefuel nozzles 94 and a center pilot fuel nozzle 96.

In operation, the fuel nozzles 80 (e.g., multi-tube fuel nozzles 94 andthe pilot fuel nozzle 96) combine fuel and air to create a fuel airmixture for combustion in the combustion zone 84. The fuel nozzles 80receive airflow from the compressor 24. As explained above, thecompressor 24 discharges airflow into an air plenum that surrounds thedownstream end 46 of the combustor 12. The radial injection apertures 78in the flow sleeve 70 enable airflow 76 to pass through the flow sleeve70 and enter the annulus 74. The annulus 74 formed by the flow sleeve 70and the combustion liner 72 guide the airflow towards the upstream end48 of the combustor 16. In the upstream end 48, the airflow 76 entersthe inlet flow conditioner 90. As will be explained in more detailbelow, the inlet flow conditioner 90 is configured to help distributethe airflow circumferentially 44 about the fuel nozzles 94, therebyhelping to provide a more equal amount of airflow into each tube 192 ofthe fuel nozzles 94. In addition, the inlet flow conditioner 90 mayfunction as a filter to help block passage of particulate matter intothe receptacles 190, thereby helping to reduce clogging of the tubes192. After passing through the inlet flow conditioner 90 the compressedair enters the tubes 192 of the multi-tube fuel nozzle 94. The tubes 192combine the compressed air with fuel 260 to create a fuel air mixture262 that combusts in the combustion zone 84. The fuel 260 radiallyenters the fuel nozzle housing 56 through the fuel flange 126. The fuel260 then passes through the second ring structure 122, the fuel strut230, and the first ring structure 120 through the respective apertures236, 238, and 240. As the fuel 260 passes through the first ringstructure 120, the fuel 260 enters the fuel nozzle receptacle 190 foruse by the fuel nozzles 94. As explained above, the radial support andfuel delivery through the fuel nozzle housing 56 enables simplificationof the endplate 54, and increases the usable surface area for themulti-tube fuel nozzles 94 (e.g., the number and/or size of themicro-mixer tubes 192).

The multi-tube fuel nozzle 94 includes multiple tubes 192 extendingthrough tube apertures 264, 266, and 268 in the respective plates 194,196, and 198. In the illustrated embodiment, the multi-tube fuel nozzle94 includes three plates 194, 196, and 198, which are axially offsetfrom one another to define chambers 270 and 272. As fuel 260 enters themulti-tube fuel nozzle 94, the fuel 260 first enters the chamber 270.Fuel 260 is distributed throughout chamber 270 before flowing downstreaminto chamber 272. The chamber 270 also helps to balance the pressure andflow of the fuel around all of the tubes 192. As illustrated, the plate196 includes apertures 274 that allow fuel to exit the chamber 270 andenter the chamber 272. In some embodiments, the tube apertures 266 mayform sufficient space for fuel to flow around the tubes 92 from chamber270 into the chamber 272. In still other embodiments, the tube apertures266 and apertures 274 may enable fuel 260 to flow from the chamber 270into the chamber 272. The apertures 266 and/or 274 are configured tohelp distribute the fuel more uniformly into the chamber 272, which thenfurther balances the pressure and flow of fuel prior to entry into thetubes 192. In the chamber 272, the fuel 260 enters the tubes 192 throughfuel inlets or slots 276 (e.g., 1 to 100 fuel inlets). As the fuel 260passes through the fuel inlets 276, the fuel 260 mixes with air 76passing through air inlets 278. The fuel air mixture 262 then travelsthrough the tubes 192 before exiting through outlets 280. In theillustrated embodiment, the fuel inlets 276 are within the chamber 272.However, in other embodiments, the fuel inlets 276 maybe in the chamber270 or in both chamber 270 and 272. In still other embodiments, the fuelnozzle 94 may exclude the plate 196, and the fuel inlets 276 may belocated between the plate 194 and the plate 198.

As explained above, the multi-tube fuel nozzle 94 may include the plates194, 196, and 198. The plates 194, 196, and 198 may be fixed or movablerelative to the tubes 192, the fuel nozzle housing 56, and/or othersupport structures of the combustor 16. For example, plates 194, 196,and 198 may have a fixed connection with the tubes 192 formed bywelding, brazing, bolting, and/or creating an interference fit. Byfurther example, a movable connection 282 (e.g., a resilient metallicseal) may be positioned between one or more of the plates 194, 196, and198 and the fuel nozzle housing 56. The movable connection 282 enablesone or more plates 194, 196, and 198 to move in the axial direction 40in response to thermal expansion and contraction of the tubes 192. Inthe illustrated embodiment, the plates 194, 196, and 198 have fixedconnections with the tubes 52, but plates 194 and 198 have movableconnections 282 (e.g., the resilient metallic seal) with the fuel nozzlehousing 56. In another embodiment, the plate 194 may have a fixedconnection with the fuel nozzle housing 56 and the tubes 192, while theplates 196 and 198 have a movable connection 282 with the fuel nozzlehousing 56. In another embodiment, the plate 198 may have a fixedconnection with the tubes 192 and a movable connection 282 (e.g., theresilient metallic seal) with the fuel nozzle housing 56, while theplates 194 and 196 have fixed connections with the fuel nozzle housing56 and movable connections (e.g., sliding joints) with the tubes 192. Inanother embodiment, the plate 196 has a fixed connection with the tubes192 and a movable connection (e.g., the resilient metallic seal) withthe fuel nozzle housing 56, while the plates 194 and 198 have fixedconnections with the fuel nozzle housing 56 and movable connections(e.g., sliding joints) with the tubes 192. In still another embodiment,each one of the plates 194, 196, and 198 may have a fixed connectionwith the tubes 192 and a movable connection (e.g., the resilientmetallic seal) with the fuel nozzle housing 56. In each of theseembodiments, the movable connections 282 (e.g., the resilient metallicseals) are configured to expand and contract in response to thermalexpansion or thermal contraction of the tubes 192, the fuel nozzlehousing 56, or any other structure of the combustor 16, thereby reducingthermally induced stresses while maintaining a fluid-tight seal.

During operation of the system 10, each tube 192 of the multi-tube fuelnozzle 94 receives approximately equal amounts of airflow through theinlet flow conditioner 90 and fuel 260 through the fuel inlets 276within the chamber 272. The fuel and air mixes within each tube 192, andthen discharges as the fuel-air mixture 262 through the fuel-air mixtureoutlet 280 for combustion within the combustor 16. As appreciated, thetemperature near the outlets 280 is elevated due to combustion withinthe combustor 16. Furthermore, the temperature of the airflow 284 may besubstantially greater than the temperature of the fuel flow 260. Forexample, the temperature of the airflow 284 may be approximately 250 to500 degrees Celsius, while the temperature of the fuel flow 260 may beapproximately 20 to 250 degrees Celsius. As a result of thesetemperature gradients, the material composition of the parts (e.g.,tubes 192, fuel nozzle housing 56, etc.), and other factors, the tubes192 may undergo a thermal expansion during operation of the micro-mixersystem 16. The movable connections 282 (e.g., resilient metallic seals)are configured to absorb this thermal expansion (and any thermalcontraction, e.g., during shutdown) to protect the various parts of themulti-tube fuel nozzles 94 and combustor 16. Without the movableconnections 282 (e.g., resilient metallic seals), the tubes 192, fuelnozzle housing 56, and other support structures may be subjected tosignificant thermal stresses, which may cause premature wear, stresscracks, and reduced life of the multi-tube fuel nozzles 94. Accordingly,the movable connections 282 (e.g., resilient metallic seals) may help toimprove the operability, performance, and life (e.g., reduced stress andfatigue) of the multi-tube fuel nozzles 94. For example, the movableconnections 282 may enable the multi-tube fuel nozzles 94 to withstandmuch greater temperature differentials, thereby allowing performanceenhancements without damaging the multi-tube fuel nozzle 94 ormicro-mixer system 16. As discussed in further detail below, the movableconnection 282 maintains a working seal between the fuel nozzle housing56 and the plates 194 and 198, while also enabling axial movement due tothe thermal expansion or contraction of the tubes 192.

FIG. 10 is a sectional view of the micro-mixer system 16 of FIG. 9,taken within line 10-10 illustrating an embodiment of a resilientmetallic seal 300 (e.g., metallic bellows 302). As discussed below, themetallic bellows 302 has a wall 303 with one or more bends or turns,which can expand and contract in the axial direction 304. As illustratedin FIG. 10, the resilient metallic seal 300 (e.g., metallic bellows 302)extends between the fuel nozzle housing 56 and the plate 198, therebyforming a working seal between the fuel nozzle housing 56 and the plate198. The plate 198 is fixed to the tubes 192, and thus the plate 198 andtubes 192 move together in response to thermal expansion and contractionwhile the resilient metallic seal 300 (e.g., metallic bellows 302)expands and contracts in the axial direction 304. In the illustratedembodiment, the resilient metallic seal 300 is disposed between the fuelnozzle housing 56 and the plate 198 in a pocket 306 (e.g., an annularpocket or sector shaped pocket), which may be formed by a groove 308(e.g., annular grove or sector shaped groove) in the fuel nozzle housing56 opposite from a peripheral portion 310 of the plate 198. The groove308 may be disposed between an inner surface 312 of the second ringstructure 120 and an inner protrusion or lip portion 314 (e.g., annularlip or sector shaped lip) of the fuel nozzle housing 56. The pocket 306(e.g., formed by the groove 308 and portions 310, 312, and 314)generally extends along the interface between the fuel nozzle housing 56and the plate 198, thereby providing a working seal that is able toexpand and contract in the axial direction 304.

In certain embodiments, the resilient metallic seal 300 (e.g., metallicbellows 302) may be fixed or unfixed (i.e., free to move) relative tothe fuel nozzle housing 56 and/or the plate 198. For example, the seal300 may have opposite first and second end portions 316 and 318, whichmay be welded, brazed, bolted, or otherwise fixed to the groove 308 andperipheral portion 310. However, one or both of the end portions 316 and318 may not be fixed to the fuel nozzle housing 56 or plate 198.Furthermore, the resilient metallic seal 300 (e.g., metallic bellows302) may have one or more flexible turns, bends, curves, folds, orgenerally axially adjustable turns 320 in the wall 303, such that theturns 320 enable the seal 300 to expand and contract in the axialdirection 304. In the illustrated embodiment, the resilient metallicseal 300 (e.g., metallic bellows 302) has multiple alternating turns 320that define a wave pattern 322. For example, the illustrated seal 300reverses direction five times, thereby defining five axially adjustableturns 320 in the wall 303. Additionally, the end portions 316 and 318maybe oriented in the radial direction 42. With the end portions 316 and318 oriented in the radial direction 42, the resilient metallic seal 300may facilitate sealing between the plate 198 and the fuel nozzle housing56. Specifically, if the pressure of the fuel in chamber 270 exceeds thepressure of the air opposite the wall 198 the metallic bellows 302 mayexpand in the axial direction 40, thus maintaining the seal. However, ifthe end portion 316 and 318 were oriented in the opposite direction themetallic bellows 302 could contract if the pressure of the fuel inchamber 270 is greater than the pressure of the air on the opposite sideof the plate 198, thus reducing the sealing force of the metallic seal300. For this reason, the orientation of the end portions 316 and 318may change depending on differing fluid pressures on opposite sides ofthe plates 194, 196, 198. For example, the metallic seals 300 coupled toplates 194 and 196 may be a metallic bellows 302 with end portions 316and 318 oriented opposite that shown in FIG. 10. This may increase theability of the metallic seals 300 in contact with the plates 194 and 196to maintain a seal with the housing 56 when the fluid pressures onopposite sides of the plates 194 and 196 differ. In other embodiments,the seal 300 may include a single axially adjustable turn 320, or anynumber of axially adjustable turns 320 (e.g., 1 to 100 turns). Thus, theturns 320 of the seal 300 may define a C-shape, a U-shape, a V-shape, aW-shape, an E-shape, or any type of oscillating pattern. In otherembodiments, the seal 300 may have an O-shape or J-shape. A largernumber of turns 320 in the resilient metallic seal 300 may increase therange of axial movement 304. The resilient metallic seal 300 may be madeof any suitable metal for high-temperature applications, such as,stainless steel grade 321, stainless steel grade 347, stainless steelA-286, nickel alloys, cobalt alloys, and nickel-chromium basedsuper-alloys (e.g., Inconel® X-750), or any combination thereof.

FIG. 11 is a front end view of an embodiment of a resilient metallicseal 300 having a sector shaped configuration 340 (e.g., a truncated-pieshape) suitable for the multi-tube fuel nozzles 94 of FIGS. 4-6. Asillustrated, the sector shaped configuration 340 includes a wedge shapeor truncated-pie shape with two generally parallel sides 342 and 344 andtwo non-parallel sides 346 and 348. The sides 342 and 344 are arcuateshaped, while sides 346 and 348 are linear (e.g., diverging in radialdirection 350). However, in certain embodiments, the sector shapedconfiguration 340 of the seal 300 may include other shapes, e.g., a pieshape with three sides. Furthermore, some embodiments of the seal 300may be shaped as a circle, a rectangle, a triangle, or other geometry.In the embodiment of FIG. 8 the multi-tube fuel nozzles 94 andassociated seals 300 may be segmented into three sectors around acentral fuel nozzle 12. However, the outer multi-tube fuel nozzles 94and associated seals 300 may be divided into any number of sectors,e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more sectors.

FIGS. 12, 13, and 14 are partial cross-sectional side views of themulti-tube fuel nozzle 94 of FIG. 9, illustrating embodiments of theresilient metallic seal 300 (e.g., metallic bellows 302) havingdifferent numbers of axially adjustable turns 320 in the wall 303. Forexample, FIG. 12 is a partial cross-sectional side view of the fuelnozzle 12 of FIG. 9, illustrating an embodiment of the resilientmetallic seal 300 having a single turn or bend 320 (e.g., a U-shape orC-shape 352). FIG. 13 is a partial cross-sectional side view of themulti-tube fuel nozzle 94 of FIG. 9, illustrating an embodiment of theresilient metallic seal 300 having multiple turns or bends 320 defininga wave pattern 322, e.g., an E-shape or W-shape 354. FIG. 14 is apartial cross-sectional side view of the multi-tube fuel nozzle 94 ofFIG. 9, illustrating an embodiment of the resilient metallic seal 300having multiple turns or bends 320 defining an even greater wave pattern322 than FIG. 10. In particular, the wave pattern 322 of FIG. 14 has 9turns or bends 320, which may be described as a wave, oscillating, orzigzagging pattern 356. In other embodiments, the pattern 356 may haveany number of turns or bends 320. For example, in applications withgreater temperature differentials, a resilient metallic seal 300 (e.g.,metallic bellows 302) with a large number of turns 320 may be used toallow for greater axial movement while still maintaining a working sealbetween the fuel nozzle housing 56 and the plate 198 of the multi-tubefuel nozzle 94. Again, in each embodiment of FIGS. 12, 13, and 14, theopposite end portions 316 and 318 may be either fixed or unfixed (i.e.,able to move) relative to the fuel nozzle housing 56 and plate 198. Forexample, one of the end portions 316 and 318 may be fixed while theother end portion is unfixed, thereby simplifying the installation andremovable of the fuel nozzles 12.

FIG. 15 is an exploded perspective view of an aft plate assembly 92. Theaft plate assembly 92 shields and cools the multi-tube fuel nozzles 94from the combustion reaction of the fuel-air mixture 262 in thecombustion zone 84, such that the aft plate assembly 92 helps to extendthe operational life of the multi-tube fuel nozzles 94. The aft plateassembly 92 includes an aft plate 370; an impingement plate 372; a firstcylinder 374 (e.g., an outer wall); a second cylinder 376 (e.g., aninner wall); and a first hoop seal 378 (e.g., hula seal) and a secondhoop seal 380 (e.g., hula seal). The hoop seals 378 and 380 aregenerally annular seals, which have an annular wall 377 that increasesthen decreases in diameter to define an arcuate cross-section or springelement 379. The accurate cross-section 379 helps to accommodate thermalexpansion and contraction in a radial direction while maintaining aseal. As illustrated, the aft plate 370 and impingement plate 372include respective tube apertures 382 and 384, which enable attachmentof the aft plate assembly 92 over the tubes 192 of the multi-tube fuelnozzle 94. The aft plate 370 and impingement plate 372 may also includerespective central nozzle apertures or passages 386 and 388. The centralnozzle apertures 386 and 388 enable the second cylinder 376 to extendthrough the impingement plate 372 and the aft plate 370 and receive thecentral fuel nozzle or pilot nozzle 96 through a central passage 385.The aft plate assembly 92 attaches to the fuel nozzle housing 56 withpins 162 (see FIG. 9), which couple to the first cylinder 374 throughapertures 390 (e.g., radial mount). The pins 162 enable the aft plateassembly 92 to grow radially, but block rotation or movement towards theaft end of the combustor 12. Furthermore, the pinned configurationenables easy replacement of the aft plate 370 or other portions of theaft plate assembly 92.

In the illustrated embodiment, each of the plates 370 and 372 receivesall of the mixing tubes 192 for the fuel nozzles 94 in multiplereceptacles (e.g., three sector shaped and/or truncated pie shapedarrangements) of the fuel nozzle housing 56. In other words, rather thanproviding a separate plate for each of the receptacles 190, theillustrated embodiment shares the plates 370 and 372 across all of thereceptacles 190, thereby defining a unified plate 370 and a unifiedplate 372. The unified aft plate 370 has tube apertures 382 disposedacross substantially all of the plate 370 in sectors (e.g., pie-shapedsectors) separated by sector dividers 381 (e.g., radial divider space),which generally align with the divider walls 242 between the receptacles190. Similarly, the unified impingement plate 372 has tube apertures 384disposed across substantially all of the plate 372 except for sectordividers 383, which generally align with the divider walls 242 betweenthe receptacles 190. Thus, the unified construction of the aft plate 370and impingement plate 372 helps to increase the coverage of tubeapertures 382 for mixing tubes 192, while also reducing the number ofpotential leak paths. The unified plates 370 and 372 also simplify theconstruction, installation, removal, and servicing of the micro mixersystem 16, and particularly the installation and removal of tubes 192.

FIG. 16 is a sectional view of the micro mixer system 16 along line16-16 of FIG. 9 according to an embodiment. As illustrated, the aftplate assembly 92 is assembled with the aft plate 370 coupled to theimpingement plate 372, and the impingement plate 372 coupled to thefirst cylinder 374. The aft plate 370, impingement plate 372, and thefirst cylinder 374 may be coupled by welding, brazing, or fasteners(e.g., threaded fasteners). Once assembled, the aft plate assembly 92couples to the fuel nozzle housing 56 with pins 162 that extend throughapertures 164 in the fuel nozzle housing 56 and apertures 390 in thefirst cylinder 374. Air flow is restricted between the aft plateassembly 92 and the combustion liner 72 with the hoop seal 378. Asmentioned above, the aft plate assembly 92 enables cooling and may blockdirect contact between the combustion of the fuel air mixture 262 in thecombustion zone 84 and the tubes 192 of the multi-tube fuel nozzles 94.Accordingly, the aft plate 370 may be made out of a material capable ofwithstanding high temperatures for long periods of time (e.g., hastalloyX, haynes 188, cobalt chromium, inconnel, etc.). In addition, the aftplate 370 may include a coating such as a thermal barrier coating (TBC)400 to provide additional thermal protection to reduce thermal wear onthe aft plate 370 and limit heat transmission to the tubes 192.

The aft plate assembly 92 may also form an air cooling chamber 402 incombination with the plate 198. As explained above, the fuel nozzlehousing 56 includes radial air cooling apertures 128 that enablecompressed air 76 traveling through the annular space 74 to enter theair cooling chamber 402. When the airflow 76 enters the chamber 402, theairflow 76 swirls around and convectively cools the tubes 192 (i.e.,transfers heat away from the tubes 192). In addition, the airflow 76 mayassist in removing any fuel 260 that is potentially leaking into the aircooling chamber 402 between the tubes 192 and the wall 198, thussubstantially reducing or eliminating fuel buildup behind the aft plate370. The chamber 402 directs the cooling airflow 76 in direction 404towards the impingement plate 372. As illustrated, the impingement plate372 is offset from the aft plate 370 to form a space 406. The space 406creates a pressure drop to attract airflow 76 through impingementapertures 408. When the airflow 76 passes through the impingement plate372, the airflow 76 impinges against a fore end side 410 of the aftplate 370 for impingement cooling of the aft plate 370. Afterimpingement cooling the fore end side 410 of the impingement plate 370,the airflow 76 may exit through effusion cooling apertures and/orbetween the aft plate 370 and the tubes 192. As the cooling air 76 exitsthe aft plate assembly 92, the airflow 76 transfers heat and possiblefuel into the combustion zone 84, thus protecting the micro-mixer system16 from thermal wear.

In other embodiments, the aft plate assembly 92 may not include animpingement plate 372. Accordingly, the cooling airflow 76 may directlycontact the fore end side 410 of the aft plate 370, and then exitthrough gaps between the tubes 192 and the aft plate 370 and/or througheffusion cooling apertures. Even with cooling, the aft plate 370 maybecome hotter than other components in the micro-mixer system 16.However, the pin attachment to the fuel nozzle housing 56 enables theaft plate assembly 92 to grow radially, but blocks rotation anddownstream axial movement. Accordingly, the micro-mixer system 16reduces or blocks mechanical loads and stresses between the aft plateassembly 92 and the fuel nozzle housing 56.

FIG. 17 is a sectional view of an aft plate 370 including tube apertures382 and effusion cooling apertures 420. As explained above, after thecooling air 76 impinges against the fore end side 410 of the aft plate370, the cooling airflow 76 may exit through effusion cooling apertures420 and/or through the tube apertures 382. As illustrated, the tubeapertures 382 have a width 422 and the tubes 192 have a width 424. Thedifference 426 between the widths 422 and 424 creates an annular space428 for the cooling airflow 76 to exit the micro-mixer system 16 throughthe aft plate 370. The cooling airflow 76 may also exit through effusioncooling apertures 420. The effusion cooling apertures 420 may be locatedbetween some or all of the tube apertures 382. In some embodiments,there may more than one effusion cooling aperture 420 between each ofthe adjacent tube apertures 382 (e.g., 1, 2, 3, 4, 5, or more). Theeffusion cooling apertures 420 may be perpendicular to the aft plate 370or form an angle with respect to a plane 432 of the aft plate 370. Forexample, the angles 430 and 431 of the effusion cooling apertures may beapproximately 30-150, 50-130, 70-110, 80-100, 30, 45, 60, 75, or 90degrees with respect the plane 432. In operation, the effusion coolingapertures 420 enable a thin film of cooling airflow to cover the aft end434 of the aft plate 370. The cooling air film may assist in protectingthe aft plate 370 from the combustion reaction in the combustor 12.While FIG. 17 illustrates an aft plate 370, the same cooling featuresmay apply to the impingement plate 372. Specifically, the impingementapertures 408 of the impingement plate 372 may form an angle withrespect to a plane of the impingement plate 372. The impingement plate372 may also include multiple impingement apertures 408 between the tubeapertures 384 (e.g., 1, 2, 3, 4, 5, or more impingement apertures) tomore effectively cool the aft plate 370.

FIG. 18 is a rear perspective view of an inlet flow conditioner 90. Asexplained above, the inlet flow conditioner 90 functions as a filter,preventing debris from entering the multi-tube fuel nozzles 94, andenables approximately even distribution of airflow to each of the tubes192 in the multi-tube fuel nozzles 94. The inlet flow conditioner 90includes a first cylinder 450 (e.g., outer wall), a second cylinder 452(e.g., an inner wall), and a plate 454 that couples the first cylinder450 to the second cylinder 452. As illustrated, the first cylinder 450includes apertures 158 that enable the inlet flow conditioner 90 tocouple to the fuel nozzle housing 56. In addition, the first cylinder450 may also include airflow apertures 456 (e.g., radial apertures)spaced apart from one another axially 40 and circumferentially 44 alongthe first cylinder 450. The apertures 456 may have a diameter smallerthan a diameter of the tubes 192 in the multi-tube fuel nozzle 94. Thedifference in diameter enables the inlet flow conditioner 90 to blockdebris in the compressed air 76 from passing through the inlet flowconditioner 90 and entering the tubes 192. In the present embodiment,the airflow apertures 456 are positioned near the plate 454. However, inother embodiments, the airflow apertures 456 may be positioned on thefirst cylinder 450 opposite the plate 454, or the airflow apertures 456may be positioned at any point about the circumference of the firstcylinder 450. In the illustrated embodiment, the airflow apertures 456are circular; however, in other embodiments the apertures may berectangular, square, or oval. Furthermore, the apertures 456 may bearranged in different patters (e.g., rows) around the first cylinder450.

The plate 454 also may include multiple airflow apertures 458 (e.g.,axial apertures). The airflow apertures 458, like apertures 456, mayhave a diameter smaller than a diameter of the tubes 192 of themulti-tube fuel nozzle 94. The difference in diameter enables the inletflow conditioner 90 to block debris in the compressed air 76 frompassing through the inlet flow conditioner 90 and entering the tubes192. As explained above, the micro-mixer system 16 delivers fuelradially 42 to the multi-tube fuel nozzles 94. Accordingly, the area ofthe plate 454 may be substantially filled with airflow apertures 458,thus reducing pressure losses as the compressed air 76 passes throughthe inlet flow conditioner 90. Like the airflow apertures 456, theairflow apertures 458 may be circular, rectangular, square, or oval.Furthermore, the airflow apertures 458 may be arranged in patterns(e.g., concentric circular rows) about the second cylinder 452. However,in different embodiments, the airflow apertures 458 may be arrangeddifferently. The second cylinder 452 rests within the plate 454 anddefines a central fuel nozzle aperture 460. The central fuel nozzleaperture 460 enables a central fuel nozzle or pilot fuel nozzle 96 topass through the inlet flow conditioner 90 and into the fuel nozzlehousing 56. In other embodiments, the inlet flow conditioner 90 may notinclude a central fuel nozzle aperture 460, but may instead includeadditional airflow apertures 458 that feed compressed air 76 into themulti-tube fuel nozzles 94.

FIG. 19 is a front perspective view of the inlet flow conditioner 90 ofFIG. 18. As illustrated, the inlet flow conditioner 90 includes dividerwalls or support plates 470 (e.g., radial supports). The support plates470 couple to the first cylinder 450, the second cylinder 452, the plate454, and to turning guides 472 (e.g., turning guide vanes, baffles, orwalls). The support plates 470 may couple by welding, brazing, orfasteners (e.g., threaded fasteners) to provide additional support forthe turning guides 472 and the second cylinder 452. In addition toproviding support, the support plates 470 may assist in channelingairflow passing through the apertures 458 in the front plate 454 to aspecific receptacle 190 and multi-tube fuel nozzle 94. In the presentembodiment, the inlet flow conditioner 90 includes three support plates470 corresponding to three multi-tube fuel nozzles 94 in the fuel nozzlehousing 56. However, in other embodiments there may be additionalsupport plates 470 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) thatmay correspond to the number of receptacles 190 and multi-tube fuelnozzles 94. Furthermore, the support plates 470 may extend from theplate 454 to an opposite end 474 of the first cylinder 450, thusdividing the airflow passing through the inlet flow conditioner 90between the multi-tube fuel nozzles 94.

Similar to the plates 370 and 372 of the aft plate assembly 92, theinlet flow conditioner 90 shown in FIGS. 18 and 19 may be a unified(e.g., one-piece) structure, which is shared among the multiplereceptacles 190, multiple fuel nozzles 94, and all of the tubes 192. Inother words, the apertures 458 may cover substantially all of the plate454 except for the support plates 470, which generally align with thedivider walls 242 between the receptacles 190. Thus, the apertures 458may help to supply the airflow substantially evenly across the entireplate 458 in an axial direction 40 toward the mixing tubes 192, whilethe apertures 456 help to supply the airflow substantially evenly aroundthe first cylinder 450 in a radial direction 42 toward the mixing tubes192. Again, the apertures 456 and 458 help to distribute the airflowmore evenly to all of the tubes 192, such that each tube 192 receives asubstantially equal amount of air flow. In addition, the unifiedconstruction of the inlet flow conditioner 90 simplifies theconstruction, installation, removal, and servicing of the fuel nozzles94 and the mixing tubes 192.

As mentioned above, the inlet flow conditioner 90 includes turningguides 472. The turning guides 472 may help to direct airflow to theradial outermost tubes 192 of the multi-tube fuel nozzles 94.Specifically, the turning guides 472 may direct airflow from the airflowapertures 456 in the first cylinder 450. In still other embodiments, theturning guides 472 may direct airflow from the apertures 456 and 458 tothe radial outermost tubes 192 of the multi-tube fuel nozzle 94, thusenabling approximately even distribution of airflow to each of the tubes192 in the multi-tube fuel nozzles 94.

FIG. 20 is a sectional view of an inlet flow conditioner 90. Asillustrated, the turning guide 472 redirects airflow entering the inletflow conditioner 90 through the apertures 456. Specifically, as airflow76 enters the inlet flow conditioner 90 through the apertures 456, theairflow contacts the turning guide 472. The turning guide 472 turns anddirects the airflow 76 to flow along the interior surface 476 of theinlet flow conditioner 90. With the airflow traveling near the interiorsurface 476, the inlet flow conditioner 90 enables the radial outermosttubes 192 to receive approximately the same amount of airflow as theradial innermost tubes 192 of the multi-tube fuel nozzles 94. In thepresent embodiment, the turning guide 472 turns the airflow entering theinlet flow conditioner 90 through the apertures 456. However, in otherembodiments, the turning guide 472 may also turn airflow entering theinlet flow conditioner 90 through some of the apertures 458 in the plate454.

FIG. 21 is a sectional view of an embodiment of the inlet flowconditioner 90. In the illustrated embodiment, the inlet flowconditioner 90 does not have a turning guide that channels airflow intothe radial outermost tubes 192 of the multi-tube fuel nozzle 94.Instead, the airflow apertures 456 form angles 480, 482, and 484 withthe first cylinder 450, wherein the angles 480, 482, and 484 aregenerally oriented in the downstream direction toward the tubes 192. Theangle of the apertures 456 redirects the airflow entering the inlet flowconditioner 90. More specifically, the angle of the apertures 456encourages airflow to flow near the inner surface 476 of the inlet flowconditioner 90, thus supplying the radial outermost tubes 192approximately the same amount of airflow that the radial innermost tubes192 receive. The angles 480, 482, and 484 may be approximately 90-170,110-150, or 130-140 degrees, or greater than approximately 100, 120,140, or 160 degrees. In some embodiments, the apertures 456 may havedifferent angles, thus encouraging the airflow through differentapertures 456 to flow closer or further away from the inner surface 476.For example, each of the angles 480, 482, and 484 may differ from oneanother, or some of the angles 480, 482, and 484 may be equal to oneanother. In another embodiment, angles 480, 482, and 484 may graduallyincrease from one aperture 456 to another in the axial direction 40. Instill another embodiment, the angles 480, 482, and 484 may graduallydecrease from one aperture 456 to another in the axial direction 40. Ineach of these embodiments, the angles of the aperture 456 may help toprovide approximately equal amounts airflow to each of the tubes 192 inthe multi-tube fuel nozzle 94.

FIG. 22 is a sectional view of an embodiment of the inlet flowconditioner 90. Similar to the embodiment in FIG. 22, the inlet flowconditioner 90 of FIG. 22 does not include a turning guide. Instead, theinlet flow conditioner 90 includes apertures 456 and 458 that formrespective angles with the first cylinder 450 and the plate 454.Specifically, apertures 456 form angles 480, 482, and 484 with the firstcylinder 450 while apertures 458 form angles 490, 492, 494, and 496. Inthe present embodiment, two of the apertures 456 have angles greaterthan ninety degrees, while the third aperture is ninety degrees withrespect to the first cylinder 450. In addition, some of the apertures458 form an angle greater than 90 degrees (e.g., angles 490 and 492)with the plate 454, while the remaining apertures 458 form ninety degreeangles 494 and 496. The combination of the two apertures 458 withnon-perpendicular angles 490 and 492 and the apertures 456 that formnon-perpendicular angles 482 and 484, all of which are greater than 90,100, 110, 120, 130, 140, 150, 160, or 170 degrees, increase the airflowalong the interior surface 476 of the first cylinder 450 to the radialoutermost tubes 192 of the multi-tube fuel nozzles 94. Accordingly, theapertures 456 in the first cylinder 450 and the apertures 458 along theplate 454 may increase airflow to the radial outermost tubes 192 of themulti-tube fuel nozzles 94, thus enabling approximately equal amounts ofairflow into the tubes 192 of the multi-tube fuel nozzle 94. The angles480, 482, 484, 490, 492, 494, and 496 may be approximately 90-170,110-150, 130-140 degrees, or approximately 90, 100, 110, 120, 130, 140,150, 160, or 170 degrees. In some embodiments, the apertures 456 and 458may have different angles, thus directing the airflow through differentapertures 456 and 458 to flow closer or further away from the innersurface 472. For example, each of the angles 480, 482, 484, 490, 492,494, and 496 may differ from one another, or may differ with respect tosome of the angles 480, 482, 484, 490, 492, 494, and 496. In anotherembodiment, angles 480, 482, and 484 may gradually increase from oneaperture to another in the axial direction 40. In still anotherembodiment, the angles 480, 482, and 484 may gradually decrease from oneaperture to another in the axial direction 40. The angles 490, 492, 494,and 496 may also gradually increase in angle from one aperture toanother in the radial direction 42 or gradually decrease in angle fromone aperture to another in the radial direction 42. Moreover, only someof the apertures 456 and 458 may form an angle greater than 90 degrees,while the remaining apertures form 90 degree angles with the firstcylinder 450 and the second cylinder 454. With each of the tubes 192receiving approximately equal amounts of airflow, via the flowconditioner 90 the multi-tube fuel nozzles 94 mix and distribute thefuel-air mixture in a suitable ratio for optimal combustion, emissions,fuel consumption, and power output. Specifically, the micro-mixer system16 may reduce levels of undesirable emissions (e.g., NOx, CO, CO₂, etc.)from a gas turbine system.

Technical effects of the invention include a modular micro-mixer system.The modular micro-mixer system facilitates inspection, maintenance, andreplacement of individual components including the multi-tube fuelnozzles, the inlet flow conditioner, the aft plate assembly, and theresilient metallic seal (e.g., a metallic bellows). As explained above,the fuel nozzle housing supports the individual components whileradially providing fuel to the multi-tube fuel nozzles. Radial fueldelivery enables use of a simplified end plate on the combustor, andincreases the available space usable by the tubes of the multi-tube fuelnozzles. Other technical effects include the inlet flow conditionercapable of filtering debris from compressed air and enablingapproximately equal amounts of airflow into each of the tubes in themulti-tube fuel nozzles. In addition, the micro-mixer system includesthe aft plate assembly configured to create a cooling air chambercapable of convectively cooling the multi-tube fuel nozzles as well asshield the multi-tube fuel nozzles from direct contact with thecombustion reaction in the combustion zone. Finally, the resilientmetallic seal reduces or blocks wear from temperature gradients withinthe multi-tube fuel nozzle. Specifically, the resilient metallic seal(e.g., metallic bellows) may expand or contract in an axial direction tolessen the effects of thermal expansion or contraction of the tubes,while maintaining a continuous working seal between the fuel nozzlehousing and the multi-tube fuel nozzles.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

1. A system, comprising: a multi-tube fuel nozzle, comprising: a firstplate having a first plurality of openings; a plurality of tubesextending through the first plurality of openings in the first plate,wherein each tube of the plurality of tubes comprises an air inlet, afuel inlet, and a fuel-air mixture outlet; and a resilient metallic sealdisposed along the first plate about the plurality of tubes.
 2. Thesystem of claim 1, comprising a combustor having the multi-tube fuelnozzle.
 3. The system of claim 2, wherein the combustor is a gas turbinecombustor.
 4. The system of claim 2, comprising a gas turbine enginehaving the combustor with the multi-tube fuel nozzle.
 5. The system ofclaim 1, wherein the multi-tube fuel nozzle comprises a second platehaving a second plurality of openings, the plurality of tubes extendsthrough the second plurality of openings in the second plate, the firstand second plates are axially offset relative to one another by an axialoffset distance, and the resilient metallic seal is configured to expandor contract in an axial direction due to axial movement between thefirst plate and the second plate, a first ring structure surrounding theplurality of tubes, or a combination thereof.
 6. The system of claim 5,wherein the first and second plates are coupled to the plurality oftubes at the axial offset distance, and the resilient metallic seal isconfigured to expand or contract in the axial direction due to thermalexpansion or thermal contraction of the plurality of tubes between thefirst and second plates.
 7. The system of claim 1, wherein the resilientmetallic seal comprises at least one flexible turn that is axiallyadjustable.
 8. The system of claim 7, wherein the at least one axiallyadjustable turn comprises a plurality of alternating turns that define awave pattern.
 9. The system of claim 7, wherein the resilient metallicseal is coupled to the first plate.
 10. The system of claim 9, whereinthe resilient metallic seal is coupled to a first ring structuresurrounding a first chamber having the plurality of tubes.
 11. Thesystem of claim 1, comprising a first ring structure surrounding a firstchamber having the plurality of tubes, wherein the first ring structurecomprises a groove and a protrusion extending around the first chamber,and the resilient metallic seal is disposed in the groove between thefirst ring structure and the first plate.
 12. The system of claim 11,wherein the resilient metallic seal is coupled to the first ringstructure.
 13. The system of claim 11, comprising a second chamberhaving the plurality of tubes, wherein the first plate axially separatesthe first and second chambers.
 14. The system of claim 13, wherein themulti-tube fuel nozzle comprises a second plate having a secondplurality of openings and a third plate having a third plurality ofopenings, wherein the plurality of tubes extend through the secondplurality of openings in the second plate and the third plurality ofopenings in the third plate, wherein the first, second, and third platesare axially offset relative to one another.
 15. A system, comprising: amulti-tube fuel nozzle, comprising: a plurality of fuel-air mixingtubes, wherein each tube of the plurality of fuel-air mixing tubescomprises an air inlet, a fuel inlet, and a fuel-air mixture outlet; anda resilient metallic seal disposed about the plurality of tubes, whereinthe resilient metallic seal comprises at least one axially adjustableturn.
 16. The system of claim 15, wherein the at least one axiallyadjustable turn comprises a plurality of alternating turns that define awave pattern.
 17. The system of claim 15, wherein the at least oneaxially adjustable turn is configured to expand or contract in an axialdirection in response to thermal expansion or thermal contraction of theplurality of fuel-air mixing tubes.
 18. The system of claim 15,comprising a combustor, a gas turbine engine, or a combination thereof,having the multi-tube fuel nozzle.
 19. A method, comprising: sealing amulti-tube fuel nozzle to a surrounding structure via a resilientmetallic seal, wherein the multi-tube fuel nozzle comprises a pluralityof tubes each having an air inlet, a fuel inlet, and a fuel-air mixtureoutlet; and expanding or contracting the resilient metallic seal, whilesealing, in response to thermal expansion or thermal contraction of theplurality of tubes or the surrounding structure.
 20. The method of claim19, wherein expanding or contracting the resilient metallic sealcomprises expanding or contracting at least one axially adjustable turnof the resilient metallic seal.